High sensitivity photodetectors, imaging arrays, and high efficiency photovoltaic devices produced using ion implantation and femtosecond laser irradiation

ABSTRACT

The present invention relates generally to methods for high throughput and controllable creation of high performance semiconductor substrates for use in devices such as high sensitivity photodetectors, imaging arrays, high efficiency solar cells and the like, to semiconductor substrates prepared according to the methods, and to an apparatus for performing the methods of the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit and priority under 35 U.S.C.§119 of U.S. Provisional Application No. 61/093,936 filed on Sep. 3,2008, and U.S. Provisional Application No. 61/155,315, filed on Feb. 25,2009, both of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates generally to methods for high throughputand controllable creation of high performance semiconductor devices suchas high sensitivity photodetectors, imaging arrays, high efficiencysolar cells and the like.

BACKGROUND

Femtosecond laser irradiation of silicon in the presence of a chalcogen(such as sulfur) under specific conditions has been shown to enablephotoactive devices with desirable characteristics. Thesecharacteristics include higher sensitivity, extended wavelengthresponse, and higher quantum efficiency at certain wavelengths thanuntreated silicon. In known systems, the sulfur (or other presentambient chemicals) is embedded into the silicon during femtosecond laserirradiation. The laser sets up a unique atomic and crystallographicarrangement in the silicon substrate. A subsequent thermal annealactivates dopant species, heals lattice damage, and results in thedesired photoactive characteristics above.

Requiring a laser to perform both dopant introduction and the subsequentunique arrangement of atoms, however, may not be as efficient or ascontrollable as needed. What is needed is a process that introduces adesired chemical species to a specific dosage level across a substratein a controllable and scalable manner, irradiates the substrate andchemical species to a desired atomic and crystalline arrangement, andactivates the electronic species contributed by the implanted atoms toproduce a semiconductor device having improved characteristics andperformance.

SUMMARY

The following is a simplified summary of the invention in order toprovide a basic understanding of some of the aspects of the invention.This summary is not intended to identify key or critical elements of theinvention or to define the scope of the invention.

An embodiment of the invention is a method for treating a semiconductorsubstrate. In an embodiment, the method comprises treating a substrateby ion implantation with an electron donating chemical species; andirradiating the substrate with a plurality of short laser pulses in aninert or vacuum environment. The substrate may be a silicon substrate.The chemical species may be a chalcogen. According to an embodiment, thechemical species may be sulfur. Where the chemical species is sulfur,sulfur may be present at an ion dosage level of between about 5×10¹⁴ and1×10¹⁶ ions/cm². Other preferred ranges and parameters for certainquantities are provided below, and are nor intended to be limiting, butmerely exemplary in description and for illustrative purposes.

The ion implantation may take place in a vacuum. In another embodiment,the environment for ion implantation may be an inert gas, for example,N₂ gas.

According to an embodiment, the method may also comprise thermalannealing of the substrate, following laser irradiation. The thermalannealing may be performed by any acceptable methods, for example, bylaser annealing, furnace annealing, or be rapid thermal annealing suchthat the substrate has an elevated temperature sufficient so as to causean increase in the charge carrier density in a microstructured layer.For example the substrate can be annealed at a temperature in a range ofabout 500° C. to about 1200° C. Again, further and preferred ranges andvalues for various parameters are provided below and in the accompanyingclaims, and these are not intended to limit the scope of the inventionbeyond that given in the claims.

According to an embodiment, the ion implantation may be performed at anenergy of between about 10 keV and about 500 keV. In another embodiment,ion implantation is performed at an energy of about 200 keV. Once again,other ranges and values of these parameters are provided herein forillustrative purposes to explain certain preferred embodiments hereof.

The present invention also includes semiconductor devices comprisingsubstrates prepared according to the methods described herein. Accordingto one embodiment, the invention may comprise a semiconductor devicecomprising a processed semiconductor substrate prepared according to themethod of claim 1. In an embodiment, a silicon substrate is processed byimplantation with sulfur, prior to laser irradiation. In an embodiment,the device may include a processed semiconductor substrate comprising atleast about 0.5×10¹⁶ sulfur ions/cm². In another embodiment, the devicemay include a processed semiconductor substrate having a responsivity ofbetween about 1 amp/watt and about 100 amp/watt. In an alternativeembodiment, the laser irradiation step is performed prior to the ionimplantation step.

In general, energetic processes which can roughen the surface of asemiconductor material, annealing, and ion implantation, as well asdoping are provided to a semiconductor material in a process or in asemiconductor device. The above are provided generally in no particularorder, and the energetic processes can include application of a laser,irradiating with a pulsed laser, or other radiative or energeticapplication of energy to the material in question.

One embodiment hereof is directed to a semiconductor processing method,including providing a semiconductor material having at least a firstsurface; implanting a dopant into the semiconductor material so as tocause a plurality of ions to be present in at least a portion of saidsemiconductor material to some depth beneath the surface; and treatingat least a portion of said surface with an energy source so as torestructure the semiconductor material in a region proximal to saidportion of the first surface being treated.

Another embodiment is directed to a method of controlling aphoto-response characteristic of a semiconductor device, including asemiconductor material having at least one surface thereof;incorporating a dopant into a region of the semiconductor materialbeneath said surface by ion implantation; and roughening said surface bysubjecting the surface to a restructuring process to yield asemiconductor device having a substantially uniform photo-responseacross at least a portion of the surface of said semiconductor device.

Yet another embodiment is directed to a photodetector device including asemiconducting substrate having a first surface; a doped region beneathsaid surface having a substantially uniform doping concentrationtherein; and a portion of said doped region proximal to said surfacebeing structurally modified by the application of an energetic processto said surface, and being substantially uniformly responsive toincident electromagnetic radiation in at least a band of wavelengths ofthe electromagnetic spectrum.

Additional features and advantages of the invention will be madeapparent from the following detailed description of illustrativeembodiments that proceeds with reference to the accompanying drawings.

IN THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawings. For the purposeof illustrating the invention, there is shown in the drawings exemplaryconstructions of the invention; however, the invention is not limited tothe specific methods and instrumentalities disclosed. Included in thedrawing are the following Figures:

FIG. 1 depicts ion implantation of a semiconductor substrate accordingto an embodiment of the invention.

FIG. 2 depicts a semiconductor substrate that has been treated with ionimplantation according to an embodiment of the invention.

FIG. 3 depicts short-pulse laser irradiation treatment of asemiconductor substrate that has been previously subjected to ionimplantation according to an embodiment of the invention.

FIG. 4 depicts a semiconductor substrate that has been treated with ionimplantation and subsequent short-pulse laser irradiation treatmentaccording to an embodiment of the invention.

FIG. 5 depicts a semiconductor substrate having a laser irradiated dopedregion prepared according to an embodiment of the invention, undergoingan anneal cycle treatment.

FIG. 6 depicts a semiconductor substrate having an annealed,laser-irradiated and doped region, prepared according to an embodimentof the invention.

FIG. 7 depicts a short-pulse laser irradiating of a semiconductorsubstrate according to an embodiment of the present invention.

FIG. 8 depicts a semiconductor substrate that has been treated with ashort-pulse laser irradiation treatment according to an embodiment ofthe present invention.

FIG. 9 depicts ion implantation of a semiconductor substrate that hasbeen treated with a short-pulse laser irradiation treatment according toan embodiment of the present invention.

FIG. 10 depicts a semiconductor substrate that has been treated withshort-pulse laser irradiation treatment and subsequent ion implantationaccording to an embodiment of the invention.

FIG. 11 depicts a semiconductor substrate having a laser irradiateddoped region prepared according to an embodiment of the invention,undergoing an anneal cycle treatment.

FIG. 12 depicts a semiconductor substrate having an annealed,laser-irradiated and doped region, prepared according to an embodimentof the invention.

FIG. 13 shows a representative current-voltage (I-V) plot from a devicewith sulfur implantation and lasing treatment, and

FIG. 14 shows an exemplary photo-detector prepared according to thepresent methods.

DETAILED DESCRIPTION

The present invention relates to improved methods of treating asemiconductor substrate to achieve dopant introduction and atomicrearrangement of the surface of a semiconductor substrate for productionof high sensitivity, extended wavelength response, i.e. about 1150nanometers (nm) to about 1200 nm, and high quantum efficiencysemiconductor materials. The invention has application in highsensitivity photodetectors, imaging arrays, and high efficiency,photovoltaic devices.

Before the present devices and methods are described, it is to beunderstood that this invention is not limited to the particularprocesses, devices, or methodologies described, as these may vary. If isalso to be understood that the terminology used in the description isfor the purpose of describing the particular versions or embodimentsonly, and is not intended to limit the scope of the present inventionwhich will be limited only by the appended claims.

In general, energetic processes which can roughen the surface of asemiconductor material, annealing, and ion implantation, as well asdoping are provided to a semiconductor material in a process or in asemiconductor device. The above are provided generally in no particularorder, and the energetic processes can include application of a laser,irradiating with a pulsed laser, coherent or non-coherent light or otherradiation, or other radiative or energetic application of energy to thematerial in question.

As used herein, and in the appended claims, the singular forms “a”, “an”and “the”include plural reference unless the context clearly dictatesotherwise. Unless defined otherwise, all technical and scientific termsused herein have the same meanings as commonly understood by one ofordinary skill in the art. Although any methods similar or equivalent tothose described herein can be used in the practice or testing ofembodiments of the present invention, the preferred methods are nowdescribed. All publications and references mentioned herein areincorporated by reference. Nothing herein is to be construed as anadmission that the invention is not entitled to antedate such disclosureby virtue of prior invention.

“Optional” or “optionally” may be taken to mean that the subsequentlydescribed structure, event or circumstance may or may not occur, andthat the description includes instances where the event occurs andinstances where it does not.

A “laser-processed” or “laser-treated” semiconductor substrate refers toa substrate that has been modified by exposure to short-pulsed lasertreatment. A short-pulsed laser is one capable of producing femtosecond,picosecond and/or nanosecond pulse durations. The surface of thesubstrate is chemically and/or structurally altered by the lasertreatment, which may, in some embodiments, result in the formation ofsurface features appearing as microstructures or patterned areas on thesurface and/or the incorporation of dopants into the substrate. Forexample, the laser treated substrate may include dopants that werepresent in a laser processing chamber during the treatment process. Thesubstrate may be treated in the presence of, for example, asulfur-containing gas or solid, or in a vacuum. Methods oflaser-processing a substrate are known, for example, those shown byCarey et al. in U.S. Pat. No. 7,057,256, the entirety of which is herebyincorporated by reference for all purposes.

Embodiments of the present invention include a process that introducesdopant through ion implantation as a controllable and scalable way toperform the first step in the process. The present invention includesthe use of ion implantation to achieve implantation of controlled closesof a desired chemical species, followed by a specific short-pulsed lasertreatment. In other embodiments, the ion implantation may follow thelaser treatment of the substrate. The doped and laser irradiatedsubstrate can be further subjected to a thermal anneal. The method ofthe invention enables high throughput and controllable creation ofvarious semiconductor devices, including but not limited to highsensitivity photodetectors, imaging arrays, and high efficiency solarcells.

An embodiment of the present invention is a method for producing highlydesirable performance characteristics in a semiconductor device.According to an embodiment, the method comprises treating a substrate byion implantation of a desired chemical species carried out to a specificdosage level, irradiating the substrate with short-pulsed laserirradiation such that a desired atomic and crystalline arrangement isobtained, and performing at least one thermal anneal cycle to activatethe electronic species contributed by the implanted atoms.

Any method for ion implantation may be used in the present invention. Inan embodiment, the energy level used for ion implantation is betweenabout 10 and about 500 keV. In another embodiment, the energy level usedis between about 50 and about 300 keV. In an embodiment, the energylevel for ion implantation is about 200 keV.

The ion dosage level may be varied depending on the specific ion to beimplanted and the chemical composition of the substrate, as would beunderstood by one of skill in the art. In an embodiment, the dosageamount of the chemical species is such that the number of chemicalspecies atoms exceeds the solid solubility limit of sulfur in silicon.In other embodiments, the dosage amount is equal to or less than thesolid solubility limit of the substrate. In an embodiment, the substrateis silicon, the chemical species comprises sulfur, and the dosage amountis such that the number of sulfur atoms exceeds the solid solubilitylimit of sulfur in silicon. In other embodiments wherein the substrateis silicon and the chemical species is sulfur, the dosage amount is suchthat the number of sulfur atoms is equal to or less than the solidsolubility limit of sulfur in silicon. For a silicon substrate beingdoped with sulfur, for example, the ion dosage levels may be betweenabout 5×10¹⁴ and 1×10¹⁶ ions/cm².

Ion implantation depth may vary depending on the energy level used andthe substrate composition. An average ion penetration depth (or “range”)may be between about 10 nanometers and about 1 micrometer.

In an embodiment, the chemical species is any atom in the periodic tableand the substrate material is any semiconductor material. In anembodiment, the chemical species is any chalcogen. In anotherembodiment, the chemical species is selenium or tellurium. In yetanother embodiment, the chemical species is a so called donor atom, suchas a phosphorous atom substituting for an atom of silicon. In anotherembodiment, the chemical species is a so called acceptor atom, such as aboron atom in silicon. According to an embodiment of invention, thechemical species is introduced in the form of ions so that a specificdosage level can be derived and controlled through electric chargecounting of ions with an apparatus such as a faraday cup.

Alternatives for doping a substrate may also be employed with thepresent invention. For example, the substrate may be grown to includethe desired amount of the dopant species. The growth method may be anepitaxial method or any other methods known to those skilled in the art.After the dopant layer is grown, a lasing step may subsequently be usedto alter the surface properties of the substrate.

In still another embodiment, the substrate may be doped through a plasmadoping process or a thermal diffusion process. In a plasma dopingprocess an energetic plasma beam that is composed of dopant ions isintroduced into the substrate. In a thermal diffusion process, dopantspecies are first coated on or near the substrate surface and thendiffused into the substrate through a thermal process, i.e. elevatingthe temperature of the substrate. A co-ion implant doping process mayalso be used according to another aspect of the present invention. Theco-ion implant process is a two step implant process that first implantsan electrically neutral specie such as fluorine or carbon into thesubstrate prior to ion implanting the active dopant species. Theelectrically neutral specie allows a better electrical activation of thedopant species in the substrate. The co-ion implant process may beperform prior to or after the lasing step. Both of these processes mayachieve a similar doped semiconductor substrate as an ion implantedstructure. One skilled in the art may choose one process over the otherto have more control of the dopant concentrations in the substrate.

In an embodiment, the step of irradiating the substrate may compriseirradiation with short-pulsed lasers such that a desired atomic andcrystalline arrangement is obtained. In an embodiment, the pulses areless than 100 nanoseconds in duration. The timescales associated withvarious mechanisms of energy transfer from excited electrons to asurrounding material dictate whether the mechanisms are thermal ornonthermal. In one embodiment, the pulses are sufficiently short induration such that the substrate cannot react in a normal thermal way.That is, the energy of a laser pulse is deposited in a time scale muchshorter than any thermal process. According to this embodiment, only theelectrons in the substrate are affected during the time the laser pulseis present. Depending on the substrate and chemical species used, thelaser pulses may be less than 50 picoseconds in duration. In anotherembodiment, the laser pulses may be less than 1 picosecond in duration.

In one aspect, a method of the invention comprises laser treating orlaser processing a substrate. In an embodiment, laser treating comprisesirradiating a surface of the substrate with one or more laser pulses.The laser pulses may have a central wavelength in a range of about 200nm to about 1200 nm, and a pulse width in a range of about tens offemtoseconds to about hundreds of nanometers. Preferably, the laserpulse widths are in a range of about 50 femtoseconds to about 50picoseconds. In an embodiment, the laser pulse widths are in the rangeof about 50 to 500 femtoseconds. The number of laser pulses irradiatingthe silicon surface can be in a range of about 1 to about 2000, and morepreferably, in a range of about 20 to about 500.

In an embodiment, the energy in each laser pulse is between 1 nanojouleand 10 microjoules. The energy density (or Fluence) of each laser pulse,in an embodiment, may be between about 0.1 kJ/m² and about 100 kJ/m². Inan embodiment, the repetition rate of the laser pulses is between 1 Hzand 60 MHz.

By way of example, the ambient environment during laser irradiation mayinclude a vacuum, an inert gas, or a gas species that contains achalcogen element (such as sulfur). In an embodiment, the ambientenvironment includes N₂ gas. In another embodiment, the gas species isH₂S. One advantage of the present invention is that it laser treatmentcan occur outside the presence of fluorine, which could otherwise beintroduced to the substrate as a contaminant. In other embodiments, thesubstrate may be prepared with a sacrificial masking configured toprotect certain regions and portions of the semiconductor substrate fromunwanted damage from the lasing process. The type of masking films usedare explained in pending U.S. application Ser. No. 12/173,903 filed onJul. 16, 2008, which is incorporated by reference herein in itsentirety. The laser treatment itself can also partially or whollyreplace a subsequent annealing step.

In an alternative embodiment, the semiconductor substrate may be treatedwith an acid bath, i.e. KOH, to achieve similar surface rougheningresults as would be accomplished with a laser irradiation step. Byplacing the semiconductor substrate in contact with an acid, surfacefeatures, such as cones, having a distance of 800 nm-100 nm from thenearest feature neighbor maybe achieved. The acid bath or surfaceetching step may be perform on the semiconductor substrate prior to orfollowing the ion implantation step but preceding the annealing step.One skilled in the art will appreciate that other known methods andreagents maybe used to create surface features on the semiconductorsubstrate.

According to an embodiment, the method of the invention comprises athermal anneal cycle, or cycles, that activate the electronic speciescontributed by the implanted atoms. Annealing can be performed accordingto a variety of methods, including, for example, furnace anneal, rapidthermal anneal, laser anneal and the like. Any process by which thetemperature of the implanted and lased substrate is raised to a desiredtemperature for a specific time is acceptable. In an embodiment,annealing is performed at between about 500° C. and 1000° C. Standardannealing requires exposure of the substrate to annealing conditions forabout 15 minutes to one hour; alternatively, rapid thermal annealing(“RTA”) (or, rapid thermal processing, “RTP”) may be performed,generally requiring much shorter anneal times, in the range of about onemillisecond to a few seconds. In an embodiment, annealing is performedusing RTA (or RTP). The desired effect of annealing is to activateelectronic carriers imparted by the ion implanted species, to healundesired lattice damage imparted to the substrate during ionimplantation and laser irradiation, and/or to engineer the implanted ionspecies chemical, atomic, and crystallographic arrangement to producedesired semiconductor device performance.

A substrate prepared according to the invention may have an activedopant concentration integrated over the ion penetration depth (or“range”) equivalent to the dosage level used during ion implantation.“Integrated over the ion penetration depth” or “integrated over therange” means the total ion concentration implanted in the substrate isequal to the integral value of the dopant concentration at differentthicknesses over the range. In an embodiment, the active dopantconcentration integrated over the range in a substrate preparedaccording to an embodiment of the invention is at least about 50% of theion dosage level used during ion implantation. Accordingly, where thechemical species used in ion implantation is sulfur and the substrate issilicon, the processed semiconductor substrate may comprise at leastabout 0.5×10¹⁶ sulfur ions/cm². In another embodiment, the active dopantconcentration integrated over the range in a substrate preparedaccording to a method of the invention is at least about 90% of the iondosage level used in ion implantation. Other levels of ion dosage may beachieved, depending on the ion used, the composition of the substrate,and the conditions of implantation, as would be understood by one ofskill in the art.

A substrate prepared according to one of the embodiments of theinvention may have a responsivity of between about 1 amp/watt and about100 amp/watt. In an embodiment, the responsivity of a substrate preparedaccording to a method of the invention has a responsivity of about 20 toabout 50 amp/watt. In another embodiment, the responsivity of asubstrate prepared according to a method of the invention has aresponsivity of about 30 amp/watt. As will be understood by one of skillin the art, the responsivity of a substrate prepared according to amethod of the invention will depend on the wavelength of the incidentradiation and the composition of the substrate.

An advantage of the present invention is increased throughput ofprocessed substrates. For example, the methods of the invention canreduce throughput time for single or multiple wafers processing to afraction of the processing time required by conventional systems. Forexample, processing that would conventionally require 60 minutes may beperformed in 5 to 15 minutes, when prepared according to certainembodiments of the invention.

An exemplary method according to the invention is represented in theFigures. An embodiment of the invention comprises ion implantation of asubstrate to yield a doped substrate, followed by laser processing ofthe substrate. FIG. 1 depicts ion implantation of a substrate, accordingto this embodiment, and FIG. 2 depicts the resulting substrate followingion implantation. A region of doped substrate is shown near thesubstrate surface. FIGS. 3 and 4 depict laser processing of the dopedsubstrate and the doped, laser treated substrate, respectively. The ionsof the doped region have been rearranged by laser treatment into acrystal formation. An optional annealing step is shown in FIG. 5, andthe annealed substrate in FIG. 6.

FIGS. 7-12 depict another exemplary method according to the presentinvention. FIG. 7 illustrates a short-pulsed laser irradiation of asemiconductor substrate. FIG. 8 depicts the resulting substratefollowing the short-pulsed laser irradiation step. FIG. 9 depicts ionimplantation of a laser irradiated substrate according to thisembodiment. A laser irradiated doped region is shown near the substratesurface in FIG. 10. In other embodiments (not shown) the laserirradiated doped region may be located near the backside of thesemiconductor substrate, such that any light incident on the substratewill penetrate and pass through a portion of the substrate prior tocontacting the laser irradiated doped region. An optional annealing stepis shown in FIG. 11, and the annealed substrate in FIG. 12.

FIG. 13 shows a representative current-voltage (I-V) plot from a devicewith sulfur implantation and lasing treatment. A responsivity of about165 A/W can be achieved at 5 volts reverse bias. The methods of theinvention differ from conventional methods in that dopant introductionby ion implantation takes the place of laser doping. This provides threedistinct advantages. 1) The dosage of the implanted chemical speciesacross a wafer/wafers can be better controlled using ion implantation,and therefore, devices prepared according to the invention will be moreuniform. For example, ion implantation routinely achieves dopantuniformity within 2% across a wafer. 2) It often takes multiple laserpulses to implant a desired chemical species to a sufficientconcentration, resulting in slow processing time and increasing theamount of undesirable laser damage done to the substrate. Ionimplantation increases throughput (state-of-the-art ion implanters reachthroughputs of over 100 wafers per hour), reduce undesirable laserdamage, and further contribute to making the process more scalable. 3)Ion implantation is a more mature and standard method for dopantintroduction than convention dopant introduction methods by laser. Aprocess flow according to an embodiment of the invention would be morecompatible with current semiconductor manufacturing processes.

FIG. 14 illustrates an embodiment of a photo-detector designed andarranged to provide certain characteristics discussed above. Forexample, the photo-detector of FIG. 14 may have certain response andsensitivity characteristics, especially at longer wavelengths. Also, thephoto-detector of FIG. 14 may be manufactured according to the stepsgiven herein to provide the cross-sectional arrangement of FIG. 14.Connections and contacts can be achieved within the device for thepurpose of connecting the device to a circuit or other electricalcomponents. In some instances the resulting apparatus comprises a solarcell responsive to solar energy.

In the specific embodiment of FIG. 14, region 1401 comprises anannealed, laser-irradiated, ion-implanted region. Region 1402 comprisesa semiconductor substrate such as silicon. Region 1403 comprises a dopedregion for making contact to metal pads or creating an internal electricfield to collect photocarriers. Region 1404 comprises metal contacts toa backside device. Region 1405 comprises a doped region to makeelectrical contact to lased regions, and is an optional region of theapparatus or device. Region 1406 comprises a doped region for makingcontact to metal pads and/or acting as a guard ring to reduce darkcurrent. Region 1407 comprises metal contacts to a frontside of saiddevice; and Region 1408 comprises a passivation layer for device activearea(s), which may comprise silicon dioxide or nitride or a combinationthereof.

In some aspects or embodiments, the present devices include asubstantially uniform photo-response across a spatial expanse of thedevice. For example, a substantially uniform responsivity can beachieved across a portion of the device's surface within a given rangeof incident wavelengths.

Without wishing to be bound by theory, the method of the invention mayimpart unique or desirable performance characteristics into thesemiconductor substrate by introduction of other atoms and unique atomicarrangements. The method of the invention can follow or precede anynumber of typical semiconductor process steps, such as dopingtreatments, passivations, oxide growths/removals, metallization steps,etc. Those knowledgeable in the art will understand that the method ofthe invention can be incorporated into various processing methodsassociated with creating a semiconductor device.

As stated earlier, one embodiment hereof is directed to a semiconductorprocessing method, including providing a semiconductor material havingat least a first surface; implanting a dopant into the semiconductormaterial so as to cause a plurality of ions to be present in at least aportion of said semiconductor material to some depth beneath thesurface; and treating at least a portion of said surface with an energysource so as to restructure the semiconductor material in a regionproximal to said portion of the first surface being treated.

In more specific preferred embodiments, the step of treating with theenergy source may include treating with a coherent light source such asa laser source. In still more specific embodiments, the laser source maybe a pulsed laser source, such as a short laser pulsed laser source. Thelength or duration of the pulses may be of almost an arbitrarycharacter, but generally designed to accomplish the present objectivesand provide the presently-described characteristics within thesemiconductor material. For example, a pulsed laser with pulse lengthsbetween about 20 femtoseconds and 50 nanoseconds is contemplated. Pulselengths between 50 nanoseconds and 500 picoseconds in duration are alsocontemplated hereby. Pulse lengths may also be between about 50femtoseconds and 50 picoseconds in duration in some embodiments.

The present method can in some embodiments provide useful devices orapparatus, and may be included in consumer, industrial, scientific,commercial, military, or other products. Certain devices made with thepresent techniques can provide a quantum efficiency of at least 40% andeven upwards of about 60% in a device that is under about 1 micrometerin thickness. In still other embodiments, this quantum efficiency may beprovided in a device having a thickness of less than about 400nanometers, or even less than about 200 nanometers.

The ion implantation energy in some embodiments may be in the range of500 eV to 500 keV. In some embodiments, the implanting may be ofpositive, negative, or electrically-neutral dopants. In a semiconductorhaving at least one surface available for treating, the dopants may bepresent in various embodiments in concentrations upward of about0.5×10¹⁶ atoms/cm³ or more in a region of the semiconductor lyingsubstantially between the surface and a depth of about 5 micrometersbelow the surface of the semiconductor. It should be noted that thesemiconductor used in one or more of the present embodiments cancomprise silicon (Si).

As to the dopant, the material may be doped in various embodiments usingany one or more of: sulfur, selenium, germanium, carbon, argon, silicon,and tellurium. The dopant can provide a “hole” or a “electron” or bechemically-neutral.

As mentioned elsewhere in this application, desirable responsivity canbe obtained from devices made and designed according to the presentmethods. For example, in some embodiments, the present methods can beused to make devices having a response of at least 0.5 Amperes/Watt(A/W) for at least one wavelength or range of wavelengths between 800nanometers and 1250 nanometers. The response of the devices can be atleast 40% greater than a response of a semiconductor material not havingundergone the present treatments. In some embodiments, the presentdevices have a response of at least 0.15 A/W for at least one wavelengthor range of wavelengths between 1150 and 1250 nanometers. It should beappreciated that the ranges given above are for illustrative purposesand other values for the present parameters may be comprehended.

The energetic process applied to the surface of the semiconductor canresult in restructuring the material at or in the vicinity of thesurface of the semiconductor. For example, crystallization can beachieved. Also, roughening of the surface can be achieved.

Again, the order in which the present steps of the process are appliedare variable. In some embodiments an annealing step is carried outbefore or during the doping step. In other embodiments an annealing stepis carried out before or during the doping step. Likewise, the annealingstep can be performed before or after or during the stated rougheningstep.

While the present invention has been described in connection with theexemplary embodiments of the various Figures, it is not limited theretoand it is to be understood that other similar embodiments may be used ormodifications and additions may be made to the described embodiments forperforming the same function of the present invention without deviatingtherefrom. Therefore, the present invention should not be limited to anysingle embodiment, but rather should be construed in breadth and scopein accordance with the appended claims. Also, the appended claims shouldbe construed to include other variants and embodiments of the invention,which may be made by those skilled in the art without departing from thetrue spirit and scope of the present invention.

1. A semiconductor processing method, comprising: providing asemiconductor material having at least a first surface; implanting adopant into the semiconductor material so as to cause a plurality ofions to be present in at least a portion of said semiconductor materialto some depth beneath the surface; and treating at least a portion ofsaid surface with an energy source so as to restructure thesemiconductor material in a region proximal to said portion of the firstsurface being treated.
 2. The method of claim 1, said treating with anenergy source comprising treating with a laser source.
 3. The method ofclaim 2, said treating with a laser source comprising treating with apulsed laser source.
 4. The method of claim 3, said treating with apulsed laser source comprising treating with a laser having pulselengths between about 20 femtoseconds and 50 nanoseconds.
 5. The methodof claim 1, providing said semiconductor material comprising providing asemiconducting material with a quantum efficiency over 40% in athickness under 1 micrometer.
 6. The method of claim 1, providing saidsemiconductor material comprising providing a semiconducting materialwith a quantum efficiency over 60% in a thickness under 400 nanometers.7. The method of claim 1, wherein the ion implant is performed at anenergy in the range of about 500 eV to about 500 keV.
 8. The method ofclaim 1, said dopant implanting causing a dopant concentration greaterthan about 0.5×10¹⁶ atoms/cm³ in said region of the semiconductormaterial to a depth of about 5 micrometers below said surface of thesemiconductor material.
 9. The method of claim 1, wherein thesemiconductor material is silicon.
 10. The method of claim 1, implantingsaid dopant comprising implanting a dopant selected from the groupconsisting of sulfur, selenium, germanium, carbon, argon, silicon andtellurium.
 11. The method of claim 1, implanting said dopant comprisingimplanting any of an electron-donating dopant, hole-donating dopant, orchemically-neutral dopant.
 12. The method of claim 1, providing saidsemiconductor material comprising providing a semiconductor materialhaving a response of at least 0.8 Ampere/Watt for at least onewavelength greater than 800 nanometers.
 13. The method of claim 12,providing said semiconductor material comprising providing asemiconductor material having a response of at least 0.8 Ampere/Watt forat least one wavelength between 800 nanometers and 1250 nanometers. 14.The method of claim 12, providing said semiconductor material comprisingproviding a semiconductor material having a response of at least 0.5Ampere/Watt for at least one wavelength between 1050 nanometers and 1250nanometers.
 15. The method of claim 12, further comprising providingsaid semiconductor material with a response that is at least 40% greaterthan a response of a semiconductor material not having undergone saidtreatment step.
 16. The method of claim 1, providing said semiconductormaterial comprising providing a semiconductor material having a responseof at least 0.15 Ampere/Watt for at least one wavelength between 1150nanometers and 1250 nanometers.
 17. A method of controlling aphotoresponse characteristic of a semiconductor device, comprising: asemiconductor material having at least one surface thereof;incorporating a dopant into a region of the semiconductor materialbeneath said surface by ion implantation; and roughening said surface bysubjecting the surface to a restructuring process to yield asemiconductor device having a substantially uniform photoresponse acrossat least a portion of the surface of said semiconductor device.
 18. Themethod of claim 17, said substantially uniform photoresponse varying byless than 20% in said portion of the surface of the semiconductordevice.
 19. The method of claim 17, said roughening by subjecting saidsurface to a restructuring process comprising subjecting said surface toa chemical etch process.
 20. The method of claim 17, said roughening bysubjecting said surface to a restructuring process comprising subjectingsaid surface to laser irradiation.
 21. The method of claim 20,subjecting said surface to laser irradiation comprising subjecting saidsurface to pulsed laser irradiation.
 22. The method of claim 17,incorporating said dopant into said region comprising substantiallyuniformly incorporating said dopant into said region of saidsemiconductor beneath said surface of said semiconductor material andacross said portion of the surface of said semiconductor material. 23.The method of claim 17, incorporating said dopant comprisingsubstantially uniformly-incorporating said dopant to a concentrationgreater than about 0.5×10¹⁶ atoms/cm³ in said region of thesemiconductor material to some depth beneath the surface of thesemiconductor material.
 24. The method of claim 17, further comprisingannealing said semiconductor material, said annealing taking placebefore or after said doping step.
 25. The method of claim 17, furthercomprising annealing said semiconductor material, said annealing takingplace before or after said roughening step.
 26. A photodetector devicecomprising: a semiconducting substrate having a first surface; a dopedregion beneath said surface having a substatially uniform dopingconcentration therein; a portion of said doped region proximal to saidsurface being structurally modified by the application of an energeticprocess to said surface, and being substantially uniformly responsive toincident electromagnetic radiation in at least a band of wavelengths ofthe electromagnetic spectrum.
 27. The photodetector of claim 26, furthercomprising connections to form a solar cell responsive to at least aband of incident electromagnetic radiation in solar energy.
 28. Thephotodetector of claim 26, being doped and treated by said energeticprocess to have a substantially uniform photoresponse in a range ofwavelengths of the electromagnetic spectrum above a given wavelengthvalue.
 29. The photodetector of claim 26, said substantially uniformphotoresponse in a range of wavelengths of the electromagnetic spectrumabove 800 nanometers.
 30. The photodetector of claim 28, said dopedregion being doped with any of sulfur, selenium, germanium, carbon,argon, silicon and tellurium.
 31. The photodetector of claim 28, saidportion of said doped region proximal to said surface being structurallymodified by the application of a laser to said portion.
 32. Thephotodetector of claim 31, said portion of said doped region proximal tosaid surface being structurally modified by the application of a pulsedlaser to said portion.